The reduction in productivity in carbonate reservoirs is often associated with near-wellbore formation damage, making matrix acidizing an essential strategy to restore permeability. In this context, treatment efficiency depends on the balance between reaction kinetics and mass transport, which governs the formation of dominant wormholes. Although additives such as corrosion inhibitors and emulsion preventers are widely used for operational purposes, their effects on the reactive behavior of acid systems remain poorly understood. This study investigates the influence of commercial additives on HCl-based acid systems, using an additive-free system (NA) as a reference. An emulsion preventer (EP), a corrosion inhibitor (CI), and a formulation containing both additives (BA) were evaluated. The EP and CI were used at concentrations of 0.2 and 0.5 vol %, respectively, and the BA formulation contained both additives at the same concentrations. The formulations were evaluated through physicochemical characterization, carbonate dissolution kinetics, and reactive-flow experiments performed on Indiana Limestone samples (18.4% average porosity and 123 mD average permeability) during the injection of 15 wt % HCl until breakthrough. The presence of additives led to a significant reduction in surface tension, suggesting changes in interfacial conditions. Batch reactor experiments showed a pronounced retardation in dissolution kinetics, with reaction times increasing by approximately 4.5-fold, 30.6-fold, and 18.2-fold for the EP, CI, and BA systems, respectively, compared with NA. In reactive-flow experiments, the minimum pore volume to breakthrough (PVbt) was reduced from 0.40 PV for the additive-free system (NA) to 0.30, 0.21, and 0.34 PV for the EP, CI, and BA systems, respectively, indicating lower acid consumption to achieve breakthrough under the evaluated laboratory conditions, with the most pronounced effect observed for the CI system. Microcomputed tomography analysis revealed that acid systems containing additives promoted the formation of dominant wormholes at lower interstitial velocities, shifting the optimal acidizing condition toward lower injection rates. Under the evaluated laboratory conditions, this behavior is likely associated with reaction retardation induced by the additives, which may reduce premature acid consumption and enable deeper wormhole propagation before significant radial enlargement occurs. The results demonstrate that acid formulation plays a key role in controlling the dissolution regime and wormhole development. Even at low concentrations, the commercial additives modified dissolution kinetics, reduced the pore volume required to achieve breakthrough, and altered wormhole development, shifting the optimum acidizing condition toward lower injection rates under the evaluated laboratory conditions. These findings demonstrate that commercial acidizing additives should be considered as active formulation components capable of modifying dissolution kinetics, acid consumption, and wormhole development under reactive-flow conditions.

Acid stimulation of carbonate rocks aims to create channels within the rock, known as wormholes, to restore or enhance permeability, increasing production. Among the acids used in this type of treatment, 15 wt % hydrochloric acid (HCl) stands out due to its high reactivity, formation of soluble reaction products in aqueous media, and cost-effectiveness. To minimize corrosion of metallic structures and avoid emulsion formation after contact with formation oil, acid solutions are commonly prepared with additives such as corrosion inhibitors and emulsion preventers. To evaluate the influence of these additives on wormhole formation, this study performed core flooding experiments at different injection rates to construct pore volume to breakthrough (PVbt) curves, both in the presence and absence of these additives. The tests employed 15 wt % HCl solutions, with and without additives, using Indiana Limestone rocks containing 98.57% calcite. The experiments were conducted in a core flooding system under an injection rate range of 0.25-16 mL/min, at 25 °C, with a confining pressure of 2000 psi and back pressure of 1200 psi. After the tests, the cores were analyzed by X-ray microcomputed tomography to evaluate wormhole formation. The results indicated that additives reduced PVbt values at low flow rates, suggesting slower reaction kinetics and higher wormhole formation efficiency. The presence of additives decreased the optimal interstitial velocity by approximately 77% (from 0.91 to 0.21 cm/min), indicating that they provide better reaction control and enhance treatment efficiency. Moreover, micro-CT images confirmed the formation of dominant wormholes at almost all flow rates in the presence of additives, whereas in their absence (e.g., at 0.5 mL/min), the sample collapsed before breakthrough. The Buijse-Glasbergen model provided a good fit to the experimental data (R 2 = 0.99) for the additive-free curve. For the additive-containing system, however, an empirical adjustment of the model exponent was required to improve the correlation (from R 2 = 0.85 to R 2 = 0.93). The results demonstrate that these additives not only inhibit corrosion and prevent emulsions but also controlled the reactivity effect. This behavior significantly broadens the scope of their application, reinforcing their strategic importance in carbonate reservoir treatments.

The Pernambuco Plateau Basin (PPB) of northeastern Brazil contains an important record of continental rifting at the boundary between the major South Atlantic basins and the Equatorial Atlantic Gateway (EAG). The geology and structure of the PPB are described using high-quality long-offset multi-channel seismic data. The deep seismic imaging reported here shows that the PPB is not thick continental crust with a thin sediment veneer, but thinned continental crust with half-graben with sediment thicknesses in excess of 3 km. Within these deep graben we find large halokinetic structures in the form of salt diapirs and pillows that root into the early synrift. Submarine volcanic edifices are also clearly imaged, the oldest of which have bases close to the synrift-to-post-rift transition. We discuss the evolution of the PPB integrating the implications of the newly observed evidence for synrift salt deposition and early post-rift submarine volcanic activity as well as a re-analysis of recent plate models. The proposed best-fit model has PPB rifting in the Aptian and early Albian, with final break-up relatively late in the Albian.

Understanding magmatic dyke emplacement requires examining the physical conditions that allow magma to propagate through the crust, specifically magma behavior, stress fields, and structural inheritance. This study focuses on the Cabo de Santo Agostinho Granite in the Pernambuco Basin, NE Brazil. As part of the Early Cretaceous Ipojuca Magmatic Suite, this granite hosts rhyolitic dykes and pseudotachylyte veins, providing a record of shallow-crustal interactions during the final stages of the South Atlantic opening. By integrating facies analysis, structural characterization, and tension estimates, we investigated whether these intrusions were linked to the final rift stages. Nine lithofacies were identified within a monzonitic batch, including dykes, injection veins, and enclaves. Structural relationships indicate that dykes propagated along pre-existing fractures independent of the stress fields associated with Cretaceous rifting. The sequence began with larger dykes followed by minor rotated intrusions. Magmatic overpressure estimates suggest a source reservoir at approximately 5-7 km depth. The pseudotachylytes likely resulted from seismic fault reactivation, where hydrous minerals like amphibole and biotite favored localized melting. Our data suggest these dykes represent the final magmatic pulses of a shallow reservoir during the plutonic evolution of the granite. Ultimately, deformation analysis confirms the intrusions occurred during the post-rift stage and were governed by local stress regimes.

We present an analysis of the ichnofossiliferous content from the Upper Campanian to the Lower Danian, obtained from well 1-PO-01-PE, Para & iacute;ba Basin, NE Brazil. The investigation integrated the bioturbation record and lithofaciological changes with delta 13C and delta 18O isotopic data to understand how variations in depositional environments and climatic conditions affected the benthic community. The analysis of core samples revealed a low diversity ichnological suite, dominated by the generalist ichnogenera Palaeophycus and Planolites, suggesting an ecosystem under ecological stress. The results suggest an intrinsic relationship between the intensity of bioturbation on the carbonate platform and sea-level changes, which controlled substrate oxygenation and energy levels. Reduced bioturbation is observed in periods associated with shallower waters and increased environmental energy (Danian), and also during the high sea-level period which may have reduced substrate oxygenation. The reduction of bioturbation during the Danian was influenced by marine regressive effects and occurred during colder climatic conditions.

Geological faults are key discontinuities in sedimentary basins and strongly influence the hydraulic and mechanical behavior of hydrocarbon reservoirs. Fault zones typically contain a low-permeability core and a more permeable damage zone, generating sharp contrasts in petrophysical and mechanical properties. Stress variations from production, injection, or geological storage may induce fault reactivation, dilatancy, and permeability enhancement, yet many numerical studies still treat faults as homogeneous features. This study develops a two-dimensional coupled hydro-mechanical framework that explicitly represents fault-core and damage-zone domains incorporating viscoelastoplastic behavior through a Mohr–Coulomb model with Perzyna viscoplasticity. The novelty of this approach lies in integrating realistic geological architecture with explicit core-damage-zone contrasts and coupled viscoelastoplastic analysis under production and injection scenarios in compartmentalized reservoirs. Based on seismic interpretation of the Laurentian Basin (offshore Canada), CODE_BRIGHT simulations model single-phase flow in a deformable reservoir to evaluate stress redistribution, permeability evolution, and deformation. Sensitivity analyses indicate that an injection pressure of 6.5 MPa triggers fault reactivation, causing dilation-induced permeability increases and establishing hydraulic communication between the deep reservoir and the overlying aquifer previously sealed by Faults 01 and 02. Fault reactivation induces an asymmetric deformational field, with horizontal displacements of approximately + 25 cm along Fault 02 and − 13 cm along Fault 01, and a distortional vertical response characterized by a dip-slip response with differential block-scale subsidence and uplift, with a maximum subsidence of 7 cm. Shear stresses concentrate mainly along Faults 01 and 02, particularly near their tips, indicating stress redistribution toward Fault 03. These results underscore the importance of internal fault-zone heterogeneity in controlling deformation, stress evolution, and transmissivity, with implications for CO2 storage, geothermal systems, industrial injection, and geotechnical applications.

During the different stages of well development and reservoir exploitation, there is the possibility of unwanted phenomena that alter the permeability of the near-wellbore region (formation damage). Well stimulation techniques seek to overcome these damages and increase oil production. Matrix acidizing in carbonate reservoirs involves acid injection, mostly hydrochloric acid (HCl), to dissolve the matrix and create pathways known as wormholes. However, the high reaction of HCl with carbonates limits its effectiveness, requiring the development of stimulation fluids to reduce the matrix dissolution rate. This study seeks to develop and evaluate retarded acid systems (RAS) composed of ethanol, 15 % HCl (w/w), and polyethoxylated nonylphenol. In core flooding experiments, the RAS demonstrated pore volume to breakthrough (PVbt) values approximate to those obtained with 15 % HCl without additives, but with flow rates 4 to 8 times lower, and produced wormhole patterns similar to the dominant ones over a wider range of injection rate. Additionally, the results indicated that the additives reduced the emulsification of HCl in heavy oil samples and demonstrated corrosion inhibition between 48 % and 54.5 %. Therefore, the promising results indicate advances in production optimization and point to interesting characteristics of these acid systems in the context of acid stimulation treatments.

This study aimed to evaluate the effects of chemical dissolution on the properties of reservoirs by matrix acidizing, using synthetic carbonate rocks with and without fractures, prepared with limestone powder, epoxy resin (chemically inert) and fractures represented by non-woven geotextile strips positioned perpendicular to the fluid flow direction, to check their influence on the dissolution process. A system was developed using an acid injection cell to carry out acidizing tests, applying a solution of acetic acid and distilled water at constant pressure, to observe the organic acid-rock interaction for contact times of 36, 72 and 108 h. Chemical and petrophysical tests, as well as image analyses using X-ray micro-computed tomography were conducted to characterize the acidizing effects. Changes in rock properties were observed as the contact time increased, particularly the increase in porosity and permeability. Was observed the formation of CO2 and calcium acetate as reaction products between calcite and acid solution. Ramified wormhole and uniform dissolution patterns were noted; moreover, fractures influenced the dissolution in regions where they were inserted, increasing the branches present along their structure and deviating the fluid flow to a perpendicular direction to the injection direction, especially observed at 72 h, highlighting the use of geotextile as a material that reproduces the fractures' transmissivity in synthetic samples. The methodologies used contributed to presenting the effects of mineral dissolution on the properties of reservoir rocks post-stimulation, emphasizing the importance of chemical/petrophysical aspects and the contribution of fractures to better understand the matrix acidizing efficiency in field.

We develop an innovative mixed-dimensional 3D/1D flow model in carbonate rocks containing multiple karst cave conduits with underlying heterogeneity in the petrophysical properties stemming from different geological stages of cave-pipe collapse systems. Such geological structures manifest in distinct heterogeneity patterns inherent to the successive stages of burial, mechanical failure, and collapse, resulting in discrete collapsed passages in the conduit network. In addition, breakdown products appear within the cave system associated with chaotic breccia, suprastrata deformation, and vertical tube-like geo-bodies, herein referred to as breccia pipes, containing faults and fractures around the vertical pipe. The input parameters of the mixed-dimensional flow model show the ability to incorporate the complex multiple heterogeneities associated with the geological objects at different stages of collapse. After populating the geo-bodies with proper petrophysical properties, the mixed-dimensional flow equations are discretized by a locally conservative extended version of the mixed-hybrid finite element method, which incorporates the new nonlinear discrete transmission jump conditions between elements adjacent to the breccias within the conduits. Computational simulations are performed for particular configurations of heterogeneous karst conduit systems with distinct geological time scales, illustrating the influence of the karst and solution breccia-pipe deposits upon the flow regimes, streamline patterns, and well productivity in real-case scenarios of hypogenic cave networks.

Este trabalho teve como objetivo caracterizar, quanto a sua origem os sedimentos que ocorrem no município de Lagoa do Carro (PE) comparando com os de Carpina (PE), assim como compreender sua proveniência. Foram coletadas 21 amostras em Lagoa do Carro e 15 amostras em Carpina. As amostras foram submetidas a análise de Minerais Pesados (MP). Foram utilizadas também as amostras de calha de 17 poços profundos perfurados no município de Lagoa do Carro, cuja finalidade foi elaborar os perfis litológicos, de modo a conhecer a espessura desse pacote sedimentar até atingir o embasamento. Os minerais pesados abundantes em Lagoa do Carro foram: magnetita, zircão, ilmenita e apatita. Menos abundantes: turmalina, rutilo e silimanita. Os raros: monazita, anfibólio e mica. Em Carpina, os abundantes: magnetita, ilmenita e turmalina. Menos abundantes: zircão, apatita e rutilo. Os raros: mica, silimanita e monazita. Sugere-se que a proveniência desses minerais seja de duas fontes: das rochas metassedimentares do Complexo Surubim-Caroalina e das rochas metaígneas do Complexo Salgadinho.

Geological CO2 Storage (GCS) in basaltic/volcanic formations is a promising avenue for mitigating anthropogenic emissions of greenhouse gases because these regions can effectively trap CO2 via mineralization. However, implementing CO2 storage projects in offshore regions demands significant investment due to the requirement to explore vast areas as well as characterize any potential prospects to verify their technical and economic feasibility. Legacy data from the oil industry could be used to provide an initial assessment of potential prospects in sedimentary basins with volcanic formations. In this study, we demonstrate the immense value of legacy products, including seismic and well log data, to identify zones with higher potential for CO2 storage. This study investigates the unconventional, mature volcanic oil reservoir of the Cabi & uacute;nas Formation in the Badejo Field, Campos Basin, Brazil, because the flood basalts that formed these reservoirs represent candidates for GCS projects in shallow water domains. Understanding the mechanism of hydrocarbon migration and accumulation in these reservoirs will provide insights into the factors that control fluid flow in basaltic rocks, helping eventual future investigation focusing CO2 storage. This investigation employed tools commonly used by the industry for exploratory investigations and reservoir characterization, based on seismic data interpretation and attribute analysis. We also performed porosity distribution estimation with an acoustic impedance inversion method based on a neural network plugin. The legacy data allowed us to characterize the complex relationships between fractures and aspects such as paleo-topography and the control of fault zones on lateral flow. We find that the relationship between faults/fractures and the apparent porosity of the volcanic succession is critical for predicting the reservoir response to CO2 injection. Legacy data from the oil industry that covers offshore regions that contain volcanic successions thus represents a valuable resource that can help save costs and accelerate the development of GCS projects.

The structural characterization of fractures is crucial to understand the processes of fluid flow in tight reservoirs. This contribution focuses on the role played by vertical fractures on the permo-porosity properties of the Aptian tight carbonate sequence of the Crato Formation, Araripe Basin (NE Brazil). The study performed a structural analysis in two different scales: reservoir scale (approximately 19.000 m2) and outcrop scale (approximately 125 m2), focusing on the fracture networks in lacustrine laminates, which have been investigated as an analogue of carbonate facies observed within the pre-salt reservoir sequence of the marginal basins in Brazil. This study employed a combination of systematic outcrop-based fracture characterization involving digital outcrop models and mechanical stratigraphy analysis. To evaluate the influence of vertical fracture systems in the fracture porosity and the equivalent permeability we performed DFN (Discrete Fracture Network) models. We focused on vertical calcite-filled fractures, oriented in two principal directions: set 1 NNW-SSE and set 2 NE-SW. Each set shows different vertical linkage patterns due to the influence of the mechanical intervals. Results of the outcrop scale model show similar behaviour for both fracture porosity and equivalent permeability, indicating that storage capacity and fluid flow may not be affected by vertical linkage of fractures. The reservoir scale DFN models show that the fracture porosity was greater in models which consider through-going continuous fractures than in models that consider the segmentation (discontinuity) of vertical fractures. Considering the vertical connectivity of fractures, the equivalent horizontal permeability (Kxx and Kyy) showed similar values in both scale models. This implies that vertical segmentation of fractures does not impact fluid flow in horizontal directions. The calculated values of equivalent vertical fracture permeability (Kzz) at reservoir scale are one order of magnitude higher in the DFNs that consider continuous fractures. Our results suggested that vertically continuous fractures enhance preferential flow pathways allowing greater vertical fluid flow than segmented fracture networks in tight carbonate reservoirs.

In recent decades, faster and more affordable methods for characterizing reservoir rocks in environmental and geological studies have gained importance, particularly for hydrocarbon exploration and resource management. One promising method is X-Ray Computed micro-Tomography (XR-?CT), enabling non-destructive analysis of rock properties. However, this technique presents challenges related to image interpretation, property characterization below the voxel scale, and result comparison across configurations. In this study, laminated limestones from the Crato Formation, analogs to the pre-salt Barra Velha Formation, were analyzed using XR-?CT to estimate density and porosity. These rocks serve as substitutes for actual reservoir conditions, addressing the challenge of limited subsurface samples. This study assessed the feasibility of XR-?CT for characterizing these properties and understanding the impact of millimeter-scale laminations on their distribution. Calibration values for calcite, the primary mineral, were used to ensure accuracy and repeatability. The results demonstrate that XR-?CT is a viable tool for environmental and geological characterization. Laminations due to stratification influenced porosity distribution in the axial direction, with higher concentrations in certain sections of the samples. The porosity values calculated using XR-?CT align relatively well with the gas porosimetry results, with most samples showing a relative difference of less than 10%. However, exceptions were observed in LM4 and T10.2, where the relative difference reached -15.90% and -12.80%, respectively. Despite these challenges, qualitative analysis was achieved. The study highlights the necessity of accounting for mineralogy and calibration in XR-?CT to ensure reliable comparisons across different tomographic systems, enhancing the method’s applicability in environmental and geological studies.

Na análise de sistemas de fraturas em geologia e engenharia, a técnica scanline é passível de viéses, podendo repercutir incertezas nos resultados. Para sanar essa fragilidade, foi desenvolvida uma ferramenta computacional de código aberto chamada Lindiwe. Assim, o objetivo deste estudo é descrever o funcionamento da ferramenta Lindiwe, desenvolvida para otimizar a análise de fraturas geológicas com base na técnica scanline. A ferramenta foi utilizada em uma simulação a partir de afloramento na Praia de Itapuama, sobre o qual foram realizados cálculos manuais pertinentes da técnica de scnaline, e fornecidas informações para a ferramenta proceder na análise. Os resultados validaram o Lindiwe, evendenciando que a ferramenta representa um avanço na análise de fraturas geológicas, proporcionando uma solução eficiente e precisa.

Characterization and development of hydrocarbon reservoirs depends on the classification of lithological patterns from well log data. In thin reservoir units, limited vertical data impedes the efficient classification of lithologies. We present a test case of petrofacies classification using machine learning models in a thin interval of finely laminated limestones using pseudo-well data created over outcrops (radiometric and unconfined compressive strength logs). We tested Gaussian naïve Bayes (GNB) and support vector machine (SVM) techniques to classify eight petrofacies types, divided into two groups. The objective was to observe the capacity of some well-known models to classify petrofacies with a high-frequency vertical variation of diagenetic heterogeneities in an extreme scenario within a thin sedimentary interval. The GNB was less effective (F 1 score of 0.29), and the SVM achieved the best results in classifying the main facies patterns (F 1 = 0.47). However, the GNB performed better when the analysis was focused on distinguishing the two main groups of petrofacies. The results demonstrate that high-frequency facies variations present a challenge to the automatic identification of lithofacies, mainly due to local variations in horizontal heterogeneities (on the mm- to cm-scale) created by depositional and diagenetic processes, which impact the flow in porous media.

Naturally fractured volcanic rocks represent a globally significant potential hydrocarbon reservoirs and can also be used for CO2 storage; however, the study of volcanic reservoirs in Brazil is limited. Although numerous volcanic reservoir types have been classified, relatively few studies are dedicated to the weathering of crust-like reservoirs, i.e., volcanic rocks undergoing subaerially alteration by weathering prior to deep burial. This study aims to characterize a volcanic weathered crust reservoir analog located in the coastal zone of the Pernambuco Basin, NE Brazil. We applied a multiscale approach motivated by the expressive potential of volcanic rocks as reservoirs in this marginal basin and considered their implications for CO2 geological storage projects. The deformational aspects observed in this analog have also been observed in other volcanic rocks that crop out in the coastal zone, thus, the data provided here can guide future characterization of both onshore and offshore reservoirs. We focused on an 80 m wide outcrop and employed geometric and topological analysis of twodimensional fracture networks to investigate the influence of regional fault zone control on the fracture permeability tensors. The parameters of fracture systems were studied using terrestrial gravimetric data, orthophoto mosaic obtained by an unmanned aerial vehicle (UAV), petrography, and outcrop-based structural data. The investigated outcrop includes porphyritic trachytes with euhedral sanidine crystals and minor quartz phenocrysts, sourced from the Ipojuca Magmatic Suite. The residual Bouguer map indicates the influence of at least two regional rift fault zones, i.e., NW-SE (strike-slip) and NE-SW (normal) trending systems, in the studied rocks. These trachytic rocks exhibited a marked dissolution of sanidine phenocrysts and matrix, columnar disjunctions, and natural fractures, causing the porosity and permeability of the reservoir analog to increase. Geometric and topological analyses showed that the south-central sector of the outcrop exhibits heightened connectivity within the fracture network. Furthermore, the principal fracture permeability is controlled by the primary families of the fracture network and regional fault zones. Our results demonstrate that the fracture network observed in the volcanic reservoir analog was influenced by the post-rift tectonic reactivation of Cretaceous structures within the Pernambuco Basin. The secondary porosity resulting from weathering and subsequent dissolution of the primary constituents and fractures of the rocks studied demonstrates the potential for the exploration of these reservoirs as models for known occurrences of volcanic rocks in the onshore and offshore domains of the Pernambuco Basin.

The Gramame and Maria Farinha formations were deposited in the Paraíba Basin during the Maastrichtian-Danian interval, recording the paleoenvironmental evolution during the opening of the Atlantic Ocean. Despite well-investigated, there is still a need to better understand the bioturbation record and the represented ecological conditions during the deposition of these units. This study investigates the ichnofauna of the carbonate facies recorded in the Itamaracá-1IT-03-PE well in the Paraíba Basin, Brazil, focusing on the paleoenvironmental characteristics that influenced this carbonate ramp. The ichnologic analysis allowed to identify environmental stress based on the limited variation in the diversity and complexity. The identified Palaeophycus-Asterosoma and Asterosoma suites suggest low to moderate energy levels, minimal fluctuations in sedimentation rates, and a relatively stress in salinity that persisted for a long period. Variations in δ13C and δ18O values during the Maastrichtian interval corroborates changes in temperature and bioproductivity, reflecting an increase in freshwater influx during this period, which affected paleoenvironmental conditions and trace fossil diversity mainly due to changes in salinity.

This study characterizes the existence of Quaternary sediments in the Transversal Zone of the Borborema Province (Northeastern Brazil). The sediments comprise paleosoils, unconsolidated sands and gravel deposits, which overlie Precambrian basement rocks. The new data on these deposits includes sedimentological and stratigraphic aspects, and age definition through quartz optically stimulated luminescence (OSL) method. The outcrops were subdivided in two broad groups (named RL and Rca) referring to nearby towns where the samples were collected. OSL ages from the RL group provided ages between ca. 160.15 +/- 38.26ka to 4.30 +/- 2.18ka, whereas the sediments in the Rca group present OSL ages from 67.45 +/- 18.24ka to 7.67 +/- 2.74ka. The geochronological results reveal that these sediments were deposited during a time period from the Pleistocene to the Holocene. Deposits are chronocorrelated to Post -Barreiras (ca. 74-2ka in age), apart from the Barreiras Formation (ca. 25 to 17Ma in age), by an expressive hiatus in the Northeast Brazil. Our investigation suggest that the sediments, in the study area, are a reworking of crystalline basement and differs genetically from PostBarreiras in the coastal zone, which are reworked from the Barreiras Formation. The combination of intense humid chemical weathering during the Pleistocene-Holocene influenced the quaternary deposition in the study area. In addition, the regional brittle tectonic reactivation of shear zones also during the Paleogene influenced the space of accommodation that allowed the deposition of these sediments.